Chlamydia trachomatis (C. trachomatis or CT) and Neisseria gonorrhoeae (N. gonorrhoeae or NG) are the causative agents of common sexually transmitted diseases. CT causes venereal lymphogranuloma, various inflammatory pathologies of the male and female urogenital systems, and trachoma, a chronic disease that affects 500 million people and can lead to blindness. When not precociously diagnosed and treated by adequate therapy, CT-induced urethritis and cervicitis may led to a variety of chronic inflammations, such as, e.g., vaginitis, salpingitis and pelvic inflammation which may result in sterility and extrauterine pregnancy. Furthermore, the new born from infected mothers may contract pulmonary and/or ocular infections during delivery.
N. gonorrhoeae, the pathogen of gonorrhoea, manifests itself as a purulent inflammation and swelling of the urethra in males. These symptoms occur in 90% of cases of infection. If left untreated, the infection can ascend and after several weeks produce symptoms of prostatitis. In women, no or only slight symptoms occur in 50% of cases of infection. The infection primarily affects the cervix, but also the urethra. In 10 to 15% of women, the infection spreads to the fallopian tubes and can also lead to sterility. Since the course of the infections is often asymptomatic, many carriers contribute unknowingly to the spread of the disease.
Considering the impact that these two organisms have, rapid and specific diagnostic tests are of utmost importance. Diagnosis based on selective growth of the pathogenic bacteria has been the standard, but cell culturing is time-consuming and many clinical isolates are difficult to grow in vitro. Infection with bacteria results in the formation of a variety of antibodies with serogroup, species, subspecies, serovar (serotype) and auxotype specificity. Sera from patients with genital tract infections have been used to diagnose CT and NG infection, however assays based on serological markers are by nature non-quantitative and subject to difficulties in interpretation. For example, antibody titres may be undetectable in acute infections (false negative), may persist in uninfected individuals with a past history of infection (false positive), may yield a false-positive indication due to the presence of cross-reacting species (e.g., respiratory infection by different Chlamydia species), or may not develop at all (false negative) depending on other factors (Ngeow, 1996, Ann Acad Med Singapore 25:300; Black et al., 1991, J Clin Microbiol 29:1312). For these reasons, serology alone is inadequate for the diagnosis of CT and NG infections.
Bacterial infections may also be diagnosed by the detection of nucleic acid sequences particular to the infectious organism. Depending on the nucleic acid sequence selected for detection, a diagnostic assay may be specific for an entire genus, more than one genus, a species or subspecies, auxotype, serovar (serotype), strain or other subset of organisms. This selectivity may be exploited in the development of simple reliable diagnostic tests for C. trachomatis and N. gonorrhoeae species of bacterial pathogens.
This background information is provided for the purpose of making known information believed by the applicant to be of possible relevance to the present invention. No admission is necessarily intended, nor should be construed, that any of the preceding information constitutes prior art against the present invention. Publications referred to throughout the specification are herein incorporated by reference in their entirety.